For more than 40 years, the central organizing concept of American defense policy has been "deterrence." The end point of analyses of superpower deterrence was that there are very few circumstances under which countries would take positive actions that might bring even a single nuclear weapon down on their heads. Yet, even as the established nuclear powers reduce total nuclear arsenals and nuclear force readiness, there are renewed worries about nuclear weapons proliferation in former Soviet states marked by economic and political upheaval and in the Middle East. Measures specifically aimed at nuclear threat situations can be broken down to (1) adding disincentives/restraints to nuclear acquisition and use and (2) devising procedures in the event of nuclear use. Changing American declaratory policy to emphasize a deliberate response to any use of weapons of mass destruction would be a disincentive. In addition, we should develop a forensic analysis capability that can identify the perpetrators to a moral certainty in the event of nuclear use.